Pneumatically operated power tools, such as sanders, are typically formed with a cast or molded housing having a chamber for receiving an air powered motor, air supply and discharge passageways communicating with the chamber through an annular side wall thereof for supplying air to and exhausting air from air supply and discharge ports of the motor, and a chamber for receiving a manually operated valve adapted to control flow of air through the air supply passageway.
In accordance with standard housing casting or molding practice, it is necessary to provide a relief for the side walls of chambers in order to permit withdrawal of chamber forming inserts from the housing at the completion of the casting or molding operation. It has been typical manufacturing practice to bore out motor receiving chambers to remove the relief and accurately size such chambers to frictionally receive a cylindrical side wall of the casing of the motor through which its air supply and exhaust ports extend. A relatively tight fit was required to be provided between the facing side walls of the chamber and motor casing in order to prevent leakage of air annularly within the chamber between the air supply and discharge passageways, and this added greatly to the cost of housing manufacture and motor assembly. An added drawback of this prior manufacturing practice is that vibrations of the motor and/or tool with which it is connected are transferred directly to the housing and from the housing to the operator of the tool.
It has been proposed to resiliently mount air motors within the chamber of an air powered tool by providing a pair of resiliently deformable bands adapted to encircle opposite ends of the motor casing, but in such installations revised motor casing and housing structures are required to permit at least one of the air supply and discharge ports of the motor casing to open axially thereof and at least one of the air supply and discharge passages to open into the chamber in an axial direction.
As with the case of motor receiving chambers, it has been common practice to bore out the valve receiving chambers of air tools to provide for a proper fit with cylindrical rotary valve sleeves, and again this adds to the cost of housing manufacture and valve installation. Another drawback of standard rotary valve constructions employed in air power tools is that they provide for non-linear adjustments of air flow in which slight rotational movements of the valve result in large changes in air flow. As a result, fine adjustments of air flow are difficult for a tool operator to achieve.
Further, various attempts have been made to provide air powered tools, such as sanders, with diverse dust collecting devices. However, prior devices of which we are aware have various disadvantages, which either result in increased tool costs or inefficiencies in the dust collection operation.